Commutator and the method of manufacturing the same.



E. A. HALBLEIB & T. L. LEE.

COMMUTATOR AND THE METHOD OF MANUFACTURING THE SAME. APPLICATION FILEDJUNE 26.1915.

1 ,274,4 1 1 v Patentea Aug. 6, 1918.

lllrnvcelmmrsz I Dam/4 8* mutator in which the UNITED STATES PATENTOFFICE.

DWARD A. HALIBLEIIB AND THOMAS L. LEE, or ROcHEsTER, NEW YORK, AssIGnoRsTo NORTH EAST ELECTRIC COMPANY, OF ROCHESTER, NEW YORK, AOORPO ATION orNEW YORK.

COMMUTATOR AND THE METHOD OF MANUFACTURING TI EE SAME.

Specification of Letters Patent.

- Application filed June 26, 1915. Serial no. 36,519.

To all whom it may concern:

Be it known that we, EDWARD A. HAmLEre and THOMAS L. LEE, citizens ofthe United States, and residents of Rochester, in the county of Monroeand State of New York, have invented certain new and useful Improvementsin Commutators and the Meth ods of Manufacturing the Same, of which thefollowing is a specification.

This invention relates to improvements in the structure and themanufacture of the commutators of electric motors, generators, or othermachines.

A commutator, as ordinarily constructed, comprises a series ofconductive bars which are mounted, with interposed insulatin material,around" a shaft, the bars eing clamped in place by collars fixed on theshaft and cojiperating with the ends of the bars, while insulatingmaterial is interposed between the bars and the collars, and usuallybetween thebars and the shaft also, to prevent short-circuits betweenthe bars. The mechanical strength of a commutator so constructed dependsupon the accuracy and firmness with which the bars are seated againstthe insulating material by which they are held in place and separatedfrom each other, and the object of the present invention is tofacilitate the manufacture of such commutators, and to produce a combarsare, in every instance, securely held against accidental displacementboth in the course of manufacture and 'n the subsequent use of thecommutator. I

It is common, in the manufacture of a' commutator, to provideoutwardly-directed,

and usually inclined, bearing-surfaces at the ends of thecommutator-bars which 7 co-- operate, through the intermediation of thinbushings of mica or other insulating material, with. theclamping-collars. ,When thesecollars are screwed up, to engage the barsfir1 t ily,'= the bars are all forced inwardly, that', i s,. toward theaxis of the shaft, so as to compress the insulating materialinterpos'edRbetween the adlacent bars, this material consisting usually:of mica, wholly or in part. Where the bars are provided only withoutwardly-directed bearing-surfaces, as just described, security againstinward displacement of any one of the bars, as a result of an accidentalblow or any other extreme accuracy cause, is afforded only by thepressure, against the slightly converging faces of the bar, exerted bythe insulating material which is interposed between the ad jacent bars,Since this material isiusually more or less compressible, especiallywhen heated, as it may be either in use or in the Patented Aug. 6, 1918.I

lateral surcourse of manufacture, sufficiently tosoften such cement asmay constitute a part of the insulating material, it has been found inpractice that in the arrangement just described the support against such'inward displacement of the bars is not alwayssufficient. In some cases,accordingly, the commutator-bars have been provided, in addition, withinwardly-directed bearing-sing faces, either at their ends, or extendingfrom one end to the other, these inwardly-directs Y bearing-surfacesbeing forced into engagement with insulating material interposed betweenthe bearing-surfaces and either the clamping-collars or the shaft. Whilesuch an arrangement, when carefully and accurately constructed, afl'ordsadequate support-f0r the bars, it is diflicult to construct a commutatorin this manner with such accuracy that all of the several parts of theinsulating material shall be brought simultaneously to the proper degreeof compression. That is to say,

ably compress the insulating material'between them, they shall also havebeen it is diflicult to insure that, in the exact position in which thebars have been moved inwardly enough to suitbrought to a firm seatagainst the insulating material engaging both their inwardlyrdirectedand their outwardly-directed bearingsurfaces.

In accordance with the present invention the commutatorrbars areprovided with bearing-surfaces both inwardly directed and outwardlydirected, and insulatingimaterial is arranged to engage both of thesesurfaces, but in order to eliminate the necessityfor in the bars and inthe thickness of the insulatingbushinggginsulab s mat r of d fislse t' ca cter s i s is employed}: tdifl'erent p'oints in the structure. Intheprefer-red embodiment of the invention the material directedbearing-surfaces may be comparatively firm and unyielding in character,and its thickness need not be gaged with extreme accuracy, because thematerial engaging the engaging the outwardlyinwardly-directedbearing-surfaces has originally a comparatively yielding character.Accordingly, when the clamping-collars are forced against the ends ofthe commutator the bars are positioned with reference to theiroutwardlydirected bearing-. surfaces and to the compression of theinsulating material interposed between the bars, while the ed againstinward movement, as well asagainst movement outwardly or in an endwisedirection.

The material which we have found to be best adapted for the purposeinquestion is a composition consisting either wholly or in part of aphenolic resin such, for example, as one of the well knownphenol-condensation products. This synthetic resin may be compoundedwith more or less paper-fiber, or other material of permanentcharacteristics, but the composition as a whole possesses to asubstantial degree the characteristics of the resinous material, thatits hardness and rigidity depends upon the degree to which it has beencured or seasoned by heat. Accordingly, the material which engages theinwardly-directed bearing-surfaces is only partially cured prior to theassembling of the elements of the commutator, so that it has still thecapacity to yield when subjected to a moderate degree of pressure. Afterthe commutator has been assembled, however, the partly cured material iscompletely cured by subjecting the assembled commutator to. heat, thuspreventing further yielding of the material, and securing the barsagainst movement in any direction; In the accompanying drawings: Figure1 is a-longitudinal sectional view of a commutator constructedinaccordance with the present invention;

Fig. 2 is a section on the line2-2 in Fig.

-1, looking from right to left in the latter figure; I

Fig. 8 is a perspective view of one of the insulatin bushings whichengages the outwardly-dlrected bearing-surfaces of the com- Imutator-bars; and; r

Fig. 4 is a perspectiveiview of one of the bushings ,which .engage theinwardly-directed bearing suiffaces on thebars.

In the illustrated commutator the central shaft-5, which may. be. thearmature-shaft of an electric generator or motor, is surrounded in theusual mannerby commute? tor-bars 6,of copper orother conductvejmaterial, and each ofthese bars 1s provlded, at

'plished I subjected to no its ends, with outwardly-directedbearingsurfaces 8, which are preferably machined to constitute elementsof a conical surface in the usual manner. The shaft is also providedwith the usual clamping-collars 9 and 10, the collar 10 beingmovablealong the shaft by means of a nut 11.

' Thin strips of insulating material are interposed between the adjacentbars, as shown in Fig. 2, and a bushing 12 of conical form is interposedbetween the clampingcollar andthe bearing-surface 7 in the usual.-

manner'. This bushing 12 may be formed of any ordinary or suitableinsulating ma terial of a comparatively unyielding character. It may, infact, be formed of. a composition characterized by the presence of aphenolic resin, provided this. resin be com pletely cured 'so as'to befirm and The present invention resides particularly in the use'ofbushings 13 interposed between the bearing-surfaces 8 and the shaft 5.These bushings are formed, as above described, of composition includingpartially cured ma u i dterial. When the parts of the illustratedcommutator are assembled, the bushings 13 are forced, in the manner ofwedges, into the angular spaces between the ends of the bars ressedagainst.

however, the

and the shaft 5, and are thus the bars. At'the same time, bushings 12force the .bars inwardly, and

since these bushings are comparatively unyielding, the final position ofthe bars is determined by the pressure of the bushings 12-, as opposedby the resistance-to compression of the insulating-material interposedbetween the-bars, and atthis time, accordingly, the bushings 13 yieldand flow suf-- ficiently to accommodate themselves to the inwardmovements of the bars.- The sur lus material of the bushings l'3 mayflow intov the space between the bars and the shaft beyond thebearing-surfaces 8, 'suflicient space being left for this purpose,although.

a sleeve 14 of insulating-material may be ness as to-interfere witdescribed.

a After the commutator has baa-esteemedas" just described it remainsonly to heat the of the heat which occurs in the commutator when itis inuse.

and prevent" any further yielding.

' interposed'between the bars andthe shaft, provided it is not ofsuch-length. or thickthe movements jus't or the commutator may be forexpress-.purpose'of curing the ins latheating operation, however,'-

A further advantage which we have found particularly in the use ofinsulating ma terial comprising a phenolic resin, residesin the factthat when this material is heated and cured, as above described, itexpands slightly, this expansion. being permanent and not merely thetemporary result of the rise in temperature. This expansion forces thematerial into any slight irregularities j in the bearing-surfaces of thebars, and into the spaces between the adjacent bars, and it alsoincreases the outward pressure against the bars, so that the structureis rendered very firm and rigid. g

While the material particularly described is the best which has yet beenfound for the purpose in question, it will be apparent that othermaterials may be employed which are.

capable of yielding when the commutator is assembled, and of beingsubsequently hardened either by the action of heat or otherwise, andaccordingly the invention is not limited to the particular materialsdescribed, or to the particular form of the parts of the commutator, orto the use of heat for the purpose of hardening the insulating material.I

.We claim:

1. The method of making commutators which consists in clampingcommutator-bars against a body of yieldin insulating matethem into saidbody and then heating the commutator to harden said substance.-

4. The methodof making commutators which consists in clampingcommutator-bars against a bod of insulating material containing aartlally cured phenolic resin, and then" heatmg the commutator to curethe resin. z

5.. A commutator, comprising commutator-bars with inwardly and outwardlydirected bearing-surfaces at their ends; clamping and supporting meansfor the bars; and insulating material interposed between said means andsaid bearing-surfaces, the insu- $0" .lating material engaging theinwardly-directed surfaces being comparatively yielding so as to permitthe position of the bars to be determined with reference to the out 1wardly-directed surfaces.

6. A commutator comprising I commutator-bars with inwardly and outwardlyinclined bearing-surfaces at their ends; a shaft; clamping-collars onthe shaft; com-p paratively-thin and rigid bushings, of insulatingmaterial, interposed between the collars and the outwardly-inclinedbearingsurfaces; and conical bushings, of comparatively yieldinginsulating material, inter-- posed between the inwardly-inclinedbearing-surfaces and the shaft.

7. The method of making a commutator comprising a rigid core,commutator-bars,

and end-members, which method consists in clamping the bars between theend-members and around the core, with a bodyvof yieldinginsulating-material interposed between the bars and the core, and thensubjecting said material to a hardening treatment.

8. The method of making a commutator comprising a rigid core,commutator-bars, and end-members, which method consists in clamping thebars between the end-members and around the core, with a body ofinsulating material, comprising incompletely cured phenolic resin,interposedbetween the bars and the'core, andthen completing the curingof said resin by theagency of heat.

- EDWARD A. HALBLEIB.

THOMA S L. LEE.

